It is 21ºC and sunny here at home at the moment. I knew it would be that warm in Aberdeen today as the BBC forecast a high of 18ºC on the national forecast (and predictably get it wrong by 3 degrees of so!). Interestingly the BBC Scotland forecast got the temperature spot on again. If they can do it why can the national forecast not, using the same data and same forecast for the same location!
I asked them this by e-mail a year ago as it is a persistent and indeed consistent shortcoming and I got a very unsatisfactory answer (and indeed incorrect!) but said they would pass it on. Their forecast are still wrong and I would guess the simple reason is that the "national resolution" takes the average land and (part of) sea temperature whereas the Scottish one takes other local factors into account. I guess we will just have to live with the temperatures being permanently incorrect on the national forecast as they know the problem yet refuse to address it.